Machines are presently available for testing the integrity of printed circuit boards by making thousands of rapid measurements of the printed electrical elements and connections situated on these boards. The contacts and connections of these boards are sequentially tested by these machines according to an interrogation program. The program instructs and directs the rapid movement of an electrical probe about the circuit board. When the probe makes contact with a board element, resistance, impedance and capacitance readings are taken to determine the integrity of the printed circuit.
One of the major problems with taking these rapidly applied measurements relates to making proper electrical contact with the conductive surfaces. Very often, the electrical probe will make a "hard landing" on conductive elements that are only a few thousandths of an inch in thickness. If the probe is caused to cavitate or mar the test surface, the electrical reading may be changed, and in severe cases, the electrical connection may be damaged or opened. It is also not uncommon for the same point on the circuit to be probed more than once. Repeated probing, even where the probe is gently applied, can introduce distortions in the circuit connection.
As printed circuits become more dense, contact points become smaller, and as measurements are more rapidly obtained and positional accuracy becomes a more important factor, the proper application of a test probe becomes critical.
Another problem in obtaining these test readings is the unevenness of the contact surfaces. Under microscopic inspection, it is often observed that printed surfaces are often rounded or sloped, rather than being flat. A probe contacting uneven surfaces may be caused to bounce or slide over these surfaces upon contact. In such situations, the connections may become damaged, or the reading may be inaccurate.
Current high technology circuit boards and demanding test probe conditions have caused a need for a new probe design and driving mechanism.
The present invention provides a new driving system and test probe configuration for the accurate and delicate testing and measurement of printed circuit connections.